This invention relates to a device for sanitising and deodorising marine toilet systems and their associated pipework, in leisure craft and small commercial craft. More specifically it overcomes the malodorous and foul smelling problems associated with such toilets by controlled injection of biodegradable disinfectant throughout the toilet system, using intelligent control.
In addition, the invention overcomes the ecologically and environmentally unfriendly habit of boat owners pouring large quantities of disinfectant into their marine toilets, in their attempts to control the malodorous and foul smells. These disinfectants are often not easily biodegradable.
Marine toilets typically use seawater, river water or lake water to flush their toilets. This water is drawn from a hull's fitting below the waterline of the boat by means of a manual or electric pump and used to flush the toilet(s). A second manual or electric pump discharges the contents of the toilet bowl into a holding tank or back into the sea, depending upon the proximity of the craft to the shore. Typically, these manual pumping systems are combined into one unit.
These toilet systems are notoriously malodorous and are the bane of many boat owners, particularly when the boat has not been used for a while as they can fill the craft with foul odours.
There are two main reasons for this.    1) The sea or river water drawn into the system contains living organisms which rapidly die and decompose due to lack of oxygen and lack of light in the pipework (or sanitation hose). Anaerobic bacteria take over and create foul smelling sulphurous gases and other compounds, which are then drawn into the toilet bowl during the flushing process and thereby released into the atmosphere inside the craft.    2) The flexible pipework (or sanitation hose) used to plumb marine heads is typically of an expanded flexible PVC material. Bacteria from both the seawater and the urine and faecal matter deposited in the toilet can, over time, penetrate and live inside the structure of the PVC. The outside of the sanitation hose running through the bilges of the craft can therefore also become continuously malodorous.
Although it is possible to partially improve the problem by putting disinfectant into the toilet bowl, this is immediately flushed away with the next flush of the toilet and the bacteria can take over again. More importantly, it is not possible to disinfect the flushing water being drawn into the toilet bowl from the sea or river, by putting disinfectant down the toilet. This is the area where some of the worst problems arise.
Some owners incur great expense by having all of the sanitation hoses on their toilets and holding tanks replaced but within a short period of time the bacteria are back, along with the odour.
Attempts have been made in the past to resolve the problem. U.S. Pat. No. 4,873,727 (17 Oct. 1989); U.S. Pat. No. 5,142,707 (1 Sep. 1992) and U.S. Pat. No. 6,295,657 (2 Oct. 2001) all try to sanitize the incumbent water, by inserting a device into the incoming sanitation hose. This device contains a block of disinfectant/detergent which gradually dissolves and disinfects the water. None of these devices appear to have proved commercially successful for the following reasons.    1) In order to have any effect, the device must be installed close to the inlet seacock and therefore under the waterline of the craft. This involves cutting or drilling holes in the sanitation hose underneath the waterline. Most sensible boat owners would be very wary of doing this as any faulty installation or failure of the device or its fittings could result in the craft sinking.    2) Replacement of the disinfectant block is extremely difficult due to its location in the boat's bilges and potentially dangerous for the reasons stated above. It therefore doesn't get replaced. U.S. Pat. No. 6,295,657 attempts to address this problem but does so by moving the device away from the seacock and thereby leaving long lengths of sanitation hose untreated.    3) If the block is replaced, the seacock has to be closed off and the device opened, thereby allowing the (by now) foul water in the sanitation hose to run out into the bilges of the craft. If the seacock is not properly closed, there is a danger of flooding the boat.    4) The rate of dissolution of the block is not controllable and leads to very concentrated disinfectant being dispensed when the toilet is little used and insufficient, when the toilet is in frequent use. This is also ecologically unfriendly.